The present invention relates generally to an internal combustion engine with a catalytic converter in its exhaust system and with a secondary air injection system, and more particularly to an overheat protection device for the catalytic converter.
It is well known to treat toxic gases, such as carbon monoxide, contained in the exhaust gases emitted by the motor vehicle utilizing an internal combustion engine by passage through a catalytic converter wherein the toxic gases are brought into contact with an oxidation catalyst and thereby undergo conversion. In such manner, carbon monoxide is converted to carbon dioxide. Heretofore, many attempts have been made to protect the thermal damage of the catalyst contained in the catalytic converter that would be caused when the catalyst temperature is raised abnormally, due to some engine trouble, such as a misfire. However, none of the conventional attempts are satisfactory.